1. Field of the Invention
The present invention relates to a process cartridge and an image forming system within which such a process cartridge can be mounted. The image forming system may be an electrophotographic copying machine, a laser beam printer (LBP), a facsimile system, a word processor or the like.
2. Related Background Art
In the past, an image forming system having a removable process cartridge including a desired process means necessary for forming an image, which thereby permits easy replacement of the cartridge due to the expiration of the service life of the cartridge or the like has been proposed (refer to U.S. Pat. No. 3,985,436). Further, a plurality of process cartridges having developer of different colors therein can be used to form a color image, and thus, have a high frequency of exchange, and in some cases, the process cartridge alone is disposed outside the image forming system. Under those circumstances, it is necessary to prevent a photosensitive member from being smudged or damaged and to prevent the photosensitive member from being exposed to light (which leads to the deterioration of the photosensitive member). To this end, the process cartridge is provided with a cover member for protecting the photosensitive member and shielding the interior of the cartridge from ambient light.
The present inventors invented particularly effective techniques in this technical field and disclosed them in U.S. Pat. Nos. 4,470,689 and 4,462,677 and in the Japanese Patent Publication No. 2-11158 (published on Mar. 13, 1990).
The present invention relates to an improvement in the above-mentioned techniques.